[Issue 16672] Deprecate "block only" delegate syntax

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=16672

--- Comment #4 from Nick Treleaven <nick at geany.org> ---
(In reply to Nick Treleaven from comment #1)
> int j;
> for({j=2; int d = 3; } j+d<7; {j++; d++;}) {

This will be caught by issue #23480.

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